The hypoxic insult that occurs in myocardial infarctions damages the myocardium it nourishes, often leading to tissue necrosis. The necrotic area becomes an inelastic scar, often leading to ventricular hypertrophy and congestive heart failure. The purpose of my research under the NRSA fellowship is to study presidentially approved WAO1 human embryonic stem (hES) cells to define populations of cardiac progenitor cells (CPCs) suitable for transplantation into the site of myocardial injury. Thus, I hope to prevent myocardial degeneration and maintain functionality. The characteristics of mouse embryonic stem cell derived CPCs have been defined in my laboratory, and will serve as a basis to establish hES cell derived CPC populations. My first aim will be to establish the genetic markers characteristic of these cells in vivo and in vitro. My second aim is to determine gene expression levels to pinpoint CPCs temporal location during hES cell differentiation. My third aim is to establish a mechanism for selection of CPCs into pure populations. My fourth aim is to evaluate purified hES CPCs proliferative potential in vitro and in vivo. Future goals would include testing the safety and therapeutic potential of these cells in the pig myocardial infarction transplant model.